docs: def _deep_copy_contours(self, ufo, parent, component, transformation):
          """Copy contours from component to parent, including nested components."""
  
          for nested in component.components:
              self._deep_copy_contours(
                  ufo,
                  parent,
                  ufo[nested.baseGlyph],
                  transformation.transform(nested.transformation),
              )
  
          if component != parent:
              pen = TransformPen(parent.getPen(), transformation)
  
              # if the transformation has a negative determinant, it will reverse
              # the contour direction of the component
              xx, xy, yx, yy = transformation[:4]
              if xx * yy - xy * yx < 0:
                  pen = ReverseContourPen(pen)
  
              component.draw(pen)